TY - THES A1 - Yin, Huajie T1 - Thermal and Dynamic Glass Transition in Ultrathin Films of Homopolymers and a Miscible Polymer Blend N2 - Dünne Polymerschichten im nanoskaligen Bereich finden heute in vielen Gebieten z. B. für Beschichtungen, als Membranen, für Sensoren oder in diversen elektronischen Geräten ihre Anwendung. Wissenschaftliche Studien belegen, dass viele physikalische Eigenschaften (Glasübergang, Kristallisation, Entnetzung, Alterung etc.) von ultradünnen Polymerschichten (Polymere in 1-dimensionaler räumlicher Begrenzung) stark von dem Verhalten im Volumen abweichen. Da die Eigenschaften eng mit der Verwendung und Funktionalität von Polymeren verknüpft sind, müssen die beobachteten Unterschiede in nanoskaliger Begrenzung genauer untersucht werden. Die vorliegende Arbeit beschäftigt sich damit, wie die Oberfläche (Luft-Polymer- Grenzfläche), die Polymer-Substrat-Wechselwirkung und die Schichtdicke die Glasübergangstemperatur (Tg) und die segmentale Dynamik (α-Relaxationsprozess) in Homopolymeren und mischbaren Polymer-Blends in dünnen Schichten beeinflussen. Komplementäre experimentelle Methoden, wie Differential Scanning Calorimetry (DSC), Capacitive Scanning Dilatometry (CSD), Breitbandige Dielektrische Spektroskopie (BDS) und Spezifische Wärme Spektroskopie (SHS) wurden angewendet, um den Glasübergang der dünnen Polymerschichten aus der thermodynamischen und kinetischen Sicht zu untersuchen. In dieser Arbeit werden die Glasübergangstemperatur und die segmentale Dynamik von ultradünnen Polymerschichten in Abhängigkeit der Schichtdicke untersucht. Für ultradünne Polycarbonatschichten (PC-Schichten, dünner als 20 nm) zwischen zwei Aluminiumschichten wurde ein Anstieg von der Glasübergangstemperatur (Tg) als auch der Vogel Temperatur (T0) mit abnehmender Schichtdicke beobachtet. BDS-Messungen zeigten einen Anstieg der segmentalen Relaxationszeit für ultradünne PC-Schichten. In den SHS-Messungen für die Siliciumdioxid (10-192 nm) basierten PC-Schichten konnte unter Einbeziehung des experimentellen Fehlers keine Abhängigkeit der segmentalen Dynamik von der Schichtdicke festgestellt werden. Diese Eigenschaften werden im Hinblick auf die Geometrie der dünnen Schichten und die relevanten Wechselwirkungsenergien zwischen dem Polymer und dem Substrat diskutiert. Im Falle von dünnen Polystyrolschichten (PS-Schichten) mit hohem Molekulargewicht (Mw) sinkt die Glasübergangstemperatur Tg mit Verringerung der Schichtdicke. Die segmentale Dynamik hängt jedoch nicht von der Stärke der Schichtdicke ab. Darüber hinaus werden für dünne PS-Schichten die Auswirkungen des Molekulargewichts Mw und Temperbedingungen auf Tg und die segmentale Dynamik untersucht. Im Bereich der dünnen Polyvinylmethyletherschichten (PVME-Schichten) konnte mittels SHS keine Abhängigkeit der segmentalen Dynamik von der Schichtdicke aufgezeigt werden. Der letzte Teil dieser Arbeit beschäftigt sich mit dünnen Schichten mischbarer Polymer-Blends mit einem Gewichtsteil von 50/50 PS/PVME. Es wurde eine Beschleunigung der segmentalen Dynamik mit geringerer Schichtdicke beobachtet. Dieses Phänomen wird mit der Oberflächenanreicherung von PVME, welches eine niedrigere Oberflächenenergie als PS aufweist, in das Polymer-Blend-System erklärt. Die segmentale Dynamik der mit PVME angereicherten freien Oberflächenschicht ist schneller als die Volumen- Dynamik. Durch die Verringerung der Schichtdicke werden diese freien Oberflächeneffekte so dominant, dass sie die gesamte segmentale Dynamik der Schichten von SHS (differenzieller AC Chip- basierten Kalorimetrie) erkennbare beeinflussen. Mittels Röntgenphotoelektronenspektroskopie (XPS) konnte die Oberflächenzusammensetzung des Films ermittelt und so die Phänomene der Oberflächenanreicherung verifiziert werden. N2 - Nowadays nanoscale thin polymer films are widely used in many fields like coatings, membranes, sensors, electronic devices and so on. Meanwhile, a lot of research work has evidenced the fact that many physical properties (glass transition, crystallization, dewetting, physical aging, etc.) of ultrathin polymer films show strong deviations from their bulk behavior. Since the aforementioned properties of polymer are closely related to their application and functionality, the discrepancies motivated us to obtain a more complete understanding of how nanoscale confinement affects the physical properties of polymer. The research work presented in this thesis is focused on understanding how the free surface (air- polymer interface), the polymer-substrate interface and the film thickness influence the glass transition temperature (Tg) and the related segmental dynamics (α-relaxation process) in both homopolymers and miscible polymer blends of thin films. Complementary experimental techniques including Differential Scanning Calorimetry (DSC), Capacitive Scanning Dilatometry (CSD), Broadband Dielectric Spectroscopy (BDS) and Specific Heat Spectroscopy (SHS) have been used to investigate the glass transition of thin polymer films from both the thermodynamic and the kinetic point of view. In the thesis the film thickness dependence of Tg and segmental dynamics of different thin polymer films have been investigated. For ultrathin polycarbonate (PC) films capped between two aluminum (Al) layers an increase of both the glass transition temperature (Tg) and Vogel temperature (T0) with decreasing film thickness (d) was observed when the thickness became lower than 20 nm. The segmental relaxation time at a fixed temperature was found to increase for the ultrathin PC film of 19 nm measured by BDS, whereas no thickness dependency of the segmental dynamics was detected within the experimental error limit for the PC films supported on silicon dioxide (SiO2) (10-192 nm) in the SHS measurements. These properties are discussed in terms of the thin film geometry and the relevant interfacial interaction between the polymer and the substrate. In the case of thin polystyrene (PS) films with high molecular weight (Mw), Tg is decreasing with reducing film thickness while the segmental dynamics is independent of film thickness. Moreover, the effects of the Mw and the annealing protocol performed on thin PS films on their Tg and segmental dynamics is studied. In the part of thin poly(vinyl methyl ether) (PVME) films, no thickness dependence of the segmental dynamics was observed in the SHS measurements. The last part of the thesis was concentrated on the thin films of a miscible polymer blend, PS/PVME with the weight fraction of 50/50. It was observed that the segmental dynamics became faster with reducing the film thickness. This phenomenon is explained in terms of surface enrichment of PVME in the polymer blend system where PVME has a lower surface energy than PS. The segmental dynamics of the PVME-enriched free surface layer are faster than the bulk dynamics. Such free surface effect becomes so predominant with reducing the film thickness that it affects the segmental dynamics of the whole films detected by SHS using differential AC chip-based calorimetry. X-ray photoelectron spectroscopy (XPS) was used to probe the surface composition in order to confirm such surface enrichment phenomena. T3 - BAM Dissertationsreihe - 117 KW - glass transition KW - specific heat spectroscopy KW - ultrathin film KW - polymer KW - broadband dielectric spectroscopy PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-418 SN - 978-3-9816380-5-9 SN - 1613-4249 VL - 117 SP - 1 EP - 133 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-41 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yin, Huajie A1 - Cangialosi, D. A1 - Schönhals, Andreas T1 - Glass transition and segmental dynamics in thin supported polystyrene films: The role of molecular weight and annealing JF - Thermochimica Acta N2 - Broadband dielectric spectroscopy (BDS), specific heat spectroscopy (HCS) and capacitive scanning dilatometry (CSD) are used to study the glass transition and segmental dynamics in thin supported polystyrene (PS) films. Different molecular weights (Mw = 50 kg/mol, Mw = 260 kg/mol, Mw = 1408 kg/mol) and annealing protocols are employed in the study. The segmental dynamics is independent of the film thickness for each Mw in the temperature window of the dielectric measurement. The thermal glass transition temperature, Tg, measured by CSD depends on the film thickness and shows also a dependence on Mw. These observations are explained in terms of the formation of irreversibly adsorbed layer due to chain adsorption on the Al substrates during annealing. KW - Thin polystyrene films KW - Glass transition KW - Segmental dynamics PY - 2013 DO - https://doi.org/10.1016/j.tca.2013.05.034 SN - 0040-6031 SN - 1872-762X VL - 566 SP - 186 EP - 192 PB - Elsevier CY - Amsterdam AN - OPUS4-28736 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yin, Huajie A1 - Schönhals, Andreas T1 - Glass Transition of Ultrathin Films of Homopolymers and Polymer Blend Investigated by Dielectric Relaxation and Specific Heat Spectroscopy T2 - Kolloqiumsvortrag, Helmholtz-Zentrum Geesthacht T2 - Kolloqiumsvortrag, Helmholtz-Zentrum Geesthacht CY - Geesthacht, Germany DA - 2013-06-21 PY - 2013 AN - OPUS4-28705 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yin, Huajie A1 - Schönhals, Andreas T1 - Molecular Mobility and Glass Transition of Thin Poly(Bisphenol A Carbonate)Films T2 - DPG Frühjahrstagung T2 - DPG Frühjahrstagung CY - Berlin, Germany DA - 2012-03-25 PY - 2012 AN - OPUS4-25707 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yin, Huajie A1 - Schönhals, Andreas T1 - Molecular Dynamics of Miscible Polymer Blend Thin Films T2 - DPG Frühjahrstagung T2 - DPG Frühjahrstagung CY - Berlin, Germany DA - 2012-03-25 PY - 2012 AN - OPUS4-25708 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yin, Huajie A1 - Schönhals, Andreas T1 - Glass transition and segmental dynamics of ultrathin poly(bisphenol A carbonate) films T2 - 6th International conference on times of polymers (TOP) and composites N2 - Broadband dielectric spectroscopy (BDS), capacitive scanning dilatometry (CSD) and differential ac-chip calorimetry (DACC) were used to examine the glass transition and segmental dynamics of ultrathin poly(bisphenol A carbonate) (PBAC) films. An increase of Vogel temperature (T0) as well as glass transition temperature (Tg) with decreasing film thickness was observed when the thickness is less than 20 nm. Moreover, the segmental relaxation time at a fixed temperature was found to increase for the aluminium (Al) capped PBAC films (<20 nm) in the BDS measurements, whereas in the DACC measurements no thickness dependency of the segmental dynamics was detected within the experimental error limit for the supported PBAC films (10-55 nm). These properties are discussed in terms of the thin film geometry and the relevant interfacial interaction between the polymer and the substrate. T2 - 6th International conference on times of polymers (TOP) and composites CY - Ischia, Italy DA - 2012-06-10 KW - Ultrathin film KW - Poly(bisphenol A carbonate) KW - Glass transition KW - Aluminium KW - Dielectric thin films KW - Differential scanning calorimetry KW - Permittivity KW - Polymer films PY - 2012 SN - 978-0-7354-1061-9 DO - https://doi.org/10.1063/1.4738399 N1 - Serientitel: AIP conference proceedings – Series title: AIP conference proceedings IS - 1459 SP - 64 EP - 67 AN - OPUS4-26349 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yin, Huajie A1 - Schönhals, Andreas T1 - Calorimetric glass transition of ultrathin poly(bisphenol A carbonate) films JF - Soft matter N2 - Specific heat spectroscopy in the frequency range from 1 Hz to 10³ Hz with a sensitivity of pJ K-1 was employed to study the glass transition behavior of ultrathin poly(bisphenol A carbonate) (PBAC) films with thicknesses ranging from 192 nm down to 10 nm. The amplitude and the phase angle of the complex differential voltage as a measure of the complex heat capacity were obtained as a function of temperature at a given frequency simultaneously. Both spectra are used to determine the dynamic glass transition temperature as a function of both the frequency and the film thickness. As the main result no thickness dependence of the dynamic glass transition temperature was observed down to a film thickness of 10 nm within the experimental uncertainty of ±3 K. The obtained data were compared with literature results in detail. PY - 2012 DO - https://doi.org/10.1039/c2sm26174j SN - 1744-683X VL - 8 IS - 35 SP - 9132 EP - 9139 PB - RSC Publ. CY - Cambridge AN - OPUS4-26379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yin, Huajie A1 - Schönhals, Andreas T1 - Calorimetric glass transition of ultrathin poly(vinyl methyl ether) films JF - Polymer N2 - Specific heat spectroscopy in the frequency range typically from 1 Hz to 1 kHz with a sensitivity of pJ/K was employed to study the glass transition behavior of ultrathin poly(vinyl methyl ether) (PVME) films with thicknesses ranging from 218 nm down to 12 nm. The amplitude and the phase angle of the complex differential voltage as a measure of the complex heat capacity were obtained as a function of temperature at a given frequency simultaneously. Both spectra are used to determine the dynamic glass transition temperature as a function of both the frequency and the film thickness. As main result no thickness dependence of the dynamic glass transition temperature was observed down to a film thickness of 12 nm within the experimental uncertainty of ±2 K. Further the width of the glass transition is independent of the film thickness which indicates that the extent of the cooperativity is essentially smaller than 12 nm. KW - Specific heat spectroscopy KW - Dynamic glass transition KW - Poly(vinyl methyl ether) PY - 2013 DO - https://doi.org/10.1016/j.polymer.2013.02.025 SN - 0032-3861 SN - 1873-2291 VL - 54 IS - 8 SP - 2067 EP - 2070 PB - Springer CY - Berlin AN - OPUS4-28011 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yin, Huajie A1 - Schönhals, Andreas T1 - Calorimetric Glass Transition of Ultrathin Films of Homopolymers and Their Blends T2 - DPG Frühjahrstagung T2 - DPG Frühjahrstagung CY - Regensburg, Germany DA - 2013-03-10 PY - 2013 AN - OPUS4-28762 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yin, Huajie A1 - Schönhals, Andreas T1 - Calorimetric Glass Transition of Thin Miscible Polymer Blend (PVME/PS) Films T2 - 15th International Conference "Polymeric Materials" T2 - 15th International Conference "Polymeric Materials" CY - Halle (Saale), Germany DA - 2012-09-12 PY - 2012 AN - OPUS4-26501 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -